Making liquid nitrogen at home

If you’ve got some time to scour eBay and $500 sitting around you can build your own liquid nitrogen plant. [Ben Krasnow] figured it all out for you and estimates he can produce a liter of the stuff for around $1.15. The process depends on a membrane to separate nitrogen from the other materials in the air around us and a cryocooler to get the gas cold enough to condense into a liquid. Other than atmospheric air, you need to pump in electricity. About 9.6 kWh per liter… yikes! Is your human hair solar panel up to that?

If you do this, remember that liquid nitrogen (BP -196° C) will condense oxygen to a liquid (BP -183° C).

Even with a membrane to separate out the nitrogen, if you then use the liquid to cool something open to the atmosphere, you run the risk of making some liquid oxygen. Liquid oxygen is neat, but you don’t want it around by accident.

You can get LN2 from commercial places for dirt cheap. This is actually more expensive than just buying it- look up air supply places in your phone book. We have 160-liter canisters of the stuff delivered to our door for like $120 or something.

The price per liter of his production isn’t all that important if you consider that he can produce it at any time, and assuming some durability, the cost of building the machine may eventually be a cost savings.

I don’t know if it’s the same in LN2 costs, but for many commodities, the larger the bulk you buy in, the cheaper things get. If I were to get a 4-5 liter flask of LN2 delivered, or even just went and picked it up, I’d expect to pay a good bit more than the 160l for $120 rate.

To HC, is it that the pot growers would be the problem, or the flaky energy sales money making stuff going on that they don’t want highlighted even more by strain put on the grid? :D

Just in case someone is actually thinking of doing this, please take the time and educate yourself on the dangers of this inert gas first.

I assume if you’re trying to make liquid nitrogen you’re aware of the immense dangers involved in handling it. Limbs don’t grow back people so do take care handling it.

But more importantly Liquid Nitrogen boils way below room temperature and gives off funny enough Nitrogen. The Germans call it Stickstoff (literally suffocating gas). Nitrogen is an inert substance that displaces Oxygen. Do not play with this stuff in your bedroom / garage. Do only in a well ventilated area or outside where the chances of it creating an unbreathable atmosphere are low.

Remember the first indication that you’re breathing in dangerous amounts of Nitrogen are that you have collapsed unconscious on the ground.

So you could also do this to make LOX I assume.
I see o2 concentrators on sale on TV so it would seem LOX production wouldn’t be that hard.
Just think of the fun at the next BBQ!

Yes I am kidding. LN2 is dangerous enough LOX would be borderline crazy.
But Part of me does wonder how a bang a powered aluminum LOX slurry would make. Thing is I am not crazy enough to think I have the skills to try it.

@Ulrich — right on for the cryocooler observation. I saw this on the Makezine blog a couple of days ago, and was sourly disappointed when it became apparent it was all based around a magic component, scored purely by luck, that does 99% of the work.

yeah such cryocoolers are quite expensive. Ive tought about using TECs, but they are only capable of cooling down to -120°C. Enough for Dry Ice but not for LN². I dont find enough information about the physical limitation of these devices and thought about making own TECs with standard-metals. I think they have no limitations like the semiconductors used in commercial TECs and reach > -120°C. Anyone, suggestions?